Instead, it will co-operate with the Waitaki Protection Trust, which will appeal Environment Canterbury's decision to grant four water-only resource consents.
The Central South Island Fish and Game Council also announced yesterday it would not appeal, but would register as an interested party if appeals were lodged.
Lower Waitaki River Management Society, a community group, has decided it will appeal.
Waitaki First chairwoman Helen Brookes said the decision not to appeal was made earlier this week after advice from its legal and planning advisers.
The decision was made to "rationalise time, finances and human resources", she said.
"It is important not who or which group appeals, but that an appeal is made in such a way that it is as tight as it can be," Dr Brookes said.
Soon after ECan announced its decision to grant water-only consents to Meridian for the power scheme, Dr Brookes said her organisation would appeal to the Environment Court.
That was still the view late last week.
Both Waitaki First and the Waitaki Protection Trust opposed the power scheme during resource consents hearings in 2007.
They shared resources and, in some cases, supported each other's evidence, ensuring there was no duplication which would waste resources.
Dr Brookes said the groups had identified common grounds for an Environment Court appeal.
"It really is better that all of that is put together by one organisation instead of two," she said.
Waitaki First would make its expert witnesses available to the trust if they were wanted for the appeal.
It would also co-operate with the trust to provide any other assistance it needed, and had already had input into the grounds for the appeal.
Central South Island Fish and Game Council chief executive Jay Graybill said it had taken legal and technical advice over ECan's decision.
Its legal advice was the decision "appeared robust".
The council remained disappointed the decision had deviated from the Waitaki catchment water allocation regional plan, prepared by a Government-appointed board in 2005, particularly in terms of the minimum flow of 150cumecs set for the river.
The consents granted Meridian variable monthly minimum flows ranging from 110 to 150cumecs.
The council argued during the 2007 hearings the the integrity of the plan should be maintained.
Mr Graybill said by being an "interested party" to any appeal, the council could maintain a watching brief and be present at the Environment Court.
Appeals will close tomorrow and at least one other organisation - the Lower Waitaki River Management Society - will appeal.
Its chairman, Bill Penno, has confirmed an appeal will be lodged because of concerns about the environmental effects of lowering the flow of the river if the scheme was built
